All targets that were still in camel case were renamed in snake case: tutorials, examples and unit tests.

Also, the naming of unit test and GUI tests were made consistent:

* the new naming for unit test targets is `<target>_ut` instead `<target>Test.`. The namespace is unchanged, `target::ut`.
* the new naming for "GUI" test targets is `<target>_uit` instead `<target>GuiTest.` The namespace is now `target::uit` instead of `target::test::ui`.

This frees up the "\_test" suffix for library test code, i.e. the test of `module_ui` does not conflict with the test library `module_ui_test`.